Carbon fiber nonwoven composite

ABSTRACT

Fiber-reinforced nonwoven composites having a wide variety of uses (e.g., leisure goods, aerospace, electronics, equipment, energy generation, mass transport, automotive parts, marine, construction, defense, sports and/or the like) are provided. The fiber-reinforced nonwoven composite includes a plurality of carbon fibers and a polymer matrix. The plurality of carbon fibers have an average fiber length from about 50 mm to about 125 mm. The fiber-reinforced nonwoven composite comprises a theoretical void volume from about 0% to about 10%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/379,968 filed Dec. 15, 2016, and which claimspriority from U.S. Provisional Patent Application No. 62/268,785 filedDec. 17, 2015, and claims the benefit of its earlier filing date under35 U.S.C. 119(e); each of U.S. patent application Ser. No. 15/379,968and U.S. Provisional Patent Application No. 62/268,785 are incorporatedherein by reference in their entirety.

TECHNICAL FIELD

The presently-disclosed invention relates generally to molded parts madeby thermoforming a nonwoven comprising staple carbon fibers.

BACKGROUND

Carbon fibers are finding many uses in modern products as reinforcementbecause of their strength and stiffness. The most common approach tousing carbon fibers is as woven fabrics or simply as filaments that arelayered down and incorporated into a resin to form a shaped part like aboat hull, a panel for a transportation vehicle, a bicycle frame, or ablade for a wind mill. For such processes, several bobbins of carbonfiber filaments are often mounted on a creel, and the filaments arepulled together as needed. For example, a creel of bobbins may feed abeaming process, a weaving process, or even a process of forming a shapeby winding filaments. However, it is fairly common to have partialbobbins left over during both the fiber manufacturing and weavingprocesses that are considered waste.

Attempts have been made to use the carbon fibers remaining on thosepartial bobbins by cutting them into staple fibers and incorporatingthem with other fibers into nonwovens that are subsequently used asreinforcement materials in composite structures. One approach to makesuch nonwovens that can be used in molding applications consists offirst forming a nonwoven by carding a blend comprising thermoplasticfibers (i.e. matrix fibers) and reinforcement fibers where the matrixthermoplastic fibers have a melting point substantially lower than themelting or degradation temperature for the reinforcement fibers. Next,the nonwoven web is needled to both consolidate it and achieve a higherdensity. This nonwoven subsequently is used to mold a part by using heatand pressure. During this process, the majority of the matrix fibers aremelted and the resulting polymer flow encases the reinforcement fibers.However, such existing nonwovens have been unable to achieve sufficientstrength while simultaneously exhibiting a low void volume.

Therefore there at least remains a need for a carbon nonwoven that canbe consolidated by molding the nonwoven into a thin part in such a wayas achieve both a high strength and a low void volume.

SUMMARY OF INVENTION

One or more embodiments of the invention may address one or more of theaforementioned problems. Certain embodiments according to the inventionprovide fiber-reinforced nonwoven composites suitable for a wide varietyof applications (e.g., leisure goods, aerospace, electronics, equipment,energy generation, mass transport, automotive parts, marine,construction, defense, sports and/or the like). In one aspect, thefiber-reinforced nonwoven composite includes a plurality of carbonfibers and a polymer matrix. The plurality of carbon fibers has anaverage fiber length from about 50 mm to about 125 mm. Moreover, thefiber-reinforced nonwoven composite comprises a theoretical void volumefrom about 0% to about 10%.

In accordance with certain embodiments of the invention, the pluralityof carbon fibers may comprise staple fibers. In some embodiments of theinvention, the plurality of carbon fibers may be uncrimped. In certainembodiments of the invention, the plurality of carbon fibers maycomprise an average length from about 60 mm to about 100 mm. In otherembodiments of the invention, the plurality of carbon fibers maycomprise an average length from about 65 mm to about 85 mm. In someembodiments of the invention, the plurality of carbon fibers maycomprise an average length of about 75 mm.

According to certain embodiments of the invention, the plurality ofcarbon fibers may comprise a linear mass density from about 0.1 dtex toabout 1.0 dtex. In other embodiments of the invention, the plurality ofcarbon fibers may comprise a linear mass density from about 0.5 dtex toabout 1.0 dtex. In further embodiments of the invention, the pluralityof carbon fibers may comprise a linear mass density of about 0.7 dtex.

In accordance with certain embodiments of the invention, the polymermatrix may comprise a plurality of polymeric staple fibers. In someembodiments of the invention, the plurality of polymeric staple fibersmay comprise at least one of a thermoplastic polymer or a thermosetpolymer. According to certain embodiments of the invention, theplurality of polymeric staple fibers may comprise at least one of apolyester, a polycarbonate, a co-polyester, a polyamide, a polyphenylenesulfone, an engineering polymer, or any combination thereof. In someembodiments of the invention, the plurality of polymeric staple fibersmay comprise a polyester. In further embodiments of the invention, theplurality of polymeric staple fibers may comprise polyethyleneterephthalate. In certain embodiments of the invention, the plurality ofpolymeric staple fibers may comprise bicomponent fibers.

According to certain embodiments of the invention, the plurality ofpolymeric staple fibers may comprise an average length from about 1 mmto about 100 mm. In other embodiments of the invention, the plurality ofpolymeric staple fibers may comprise an average length from about 1 mmto about 50 mm. In further embodiments of the invention, the pluralityof polymeric staple fibers may comprise an average length of about 38mm.

According to certain embodiments of the invention, the plurality ofpolymeric staple fibers may comprise a linear mass density from about1.0 dtex to about 3.0 dtex. In other embodiments of the invention, theplurality of polymeric staple fibers may comprise a linear mass densityfrom about 1.3 dtex to about 1.8 dtex. In further embodiments of theinvention, the plurality of polymeric staple fibers may comprise alinear mass density of about 1.6 dtex.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a basis weight fromabout 100 gsm to about 5000 gsm, alternatively, from about 500 gsm toabout 5000 gsm. In other embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a basis weight fromabout 1000 gsm to about 4000 gsm. In further embodiments of theinvention, the fiber-reinforced nonwoven composite may comprise a basisweight from about 2000 gsm to about 3000 gsm. In some embodiments of theinvention, the fiber-reinforced nonwoven composite may comprise a basisweight of about 2500 gsm.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise an average thicknessfrom about 0.25 mm to about 5 mm, alternatively from about 1 mm to about5 mm. In further embodiments of the invention, the fiber-reinforcednonwoven composite may comprise an average thickness of about 2 mm.According to certain embodiments of the invention, the fiber-reinforcednonwoven composite may comprise a composite density from about 1 g/cm³to about 5 g/cm³. In other embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a composite densityfrom about 1 g/cm³ to about 2 g/cm³. In further embodiments of theinvention, the fiber-reinforced nonwoven composite may comprise acomposite density from about 1.3 g/cm³ to about 1.5 g/cm³.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 10 wt. % toabout 100 wt. % carbon fiber and from about 0 wt. % to about 90 wt. %polymer matrix. In other embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 10 wt. % toabout 90 wt. % carbon fiber and from about 10 wt. % to about 90 wt. %polymer matrix. In further embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 10 wt. % toabout 60 wt. % carbon fiber and from about 40 wt. % to about 90 wt. %polymer matrix. According to certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 20 wt. % toabout 50 wt. % carbon fiber and from about 50 wt. % to about 80 wt. %polymer matrix. In some embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 30 wt. % toabout 40 wt. % carbon fiber and from about 60 wt. % to about 70 wt. %polymer matrix.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a theoretical voidvolume from about −10% to about 15%. According to certain embodiments ofthe invention, the fiber-reinforced nonwoven composite may comprise atheoretical void volume from about 0% to about 7%. In some embodimentsof the invention, the fiber-reinforced nonwoven composite may comprise atheoretical void volume from about 0% to about 5%.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a [0/90] lay-up. Insome embodiments of the invention, the fiber-reinforced nonwovencomposite may comprise about 40 wt. % carbon fiber and about 60 wt. %thermoplastic polymer matrix. In such embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a tensile modulus fromabout 15 GPa to about 50 GPa. Moreover, the fiber-reinforced nonwovencomposite may comprise a tensile strength from about 140 MPa to about600 MPa. In addition, the fiber-reinforced nonwoven composite maycomprise a flexural modulus from about 15 GPa to about 50 GPa.Furthermore, the fiber-reinforced nonwoven composite may comprise aflexural strength from about 290 MPa to about 465 MPa. In otherembodiments of the invention, the fiber-reinforced nonwoven compositemay comprise about 30 wt. % carbon fiber and about 70 wt. %thermoplastic polymer matrix. In such embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a tensile modulus fromabout 15 GPa to about 30 GPa. Moreover, the fiber-reinforced nonwovencomposite may comprise a tensile strength from about 220 MPa to about310 MPa. In addition, the fiber-reinforced nonwoven composite maycomprise a flexural modulus from about 10 GPa to about 25 GPa.Furthermore, the fiber-reinforced nonwoven composite may comprise aflexural strength from about 315 MPa to about 385 MPa.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may further comprise an epoxy resin.According to certain embodiments of the invention, the fiber-reinforcednonwoven composite may comprise a structural element utilized in anindustry selected from the group consisting of leisure goods, aerospace,electronics, equipment, energy generation, mass transport, automotiveparts, marine, construction, defense, and sports.

In another aspect, certain embodiments of the invention provide aprocess for forming a fiber-reinforced nonwoven composite. The processincludes opening a plurality of carbon fibers and a plurality ofpolymeric staple fibers, blending the plurality of carbon fibers withthe plurality of polymeric staple fibers to form a fiber blend, cardingthe fiber blend to form one or more homogenous webs, forming afiber-reinforced nonwoven from the one or more homogenous webs, andmolding the fiber-reinforced nonwoven to form a fiber-reinforcednonwoven composite. The plurality of carbon fibers may have an averagefiber length from about 50 mm to about 125 mm. Moreover, thefiber-reinforced nonwoven composite may comprise a theoretical voidvolume from about 0% to about 10%. According to certain embodiments ofthe invention, blending the plurality of carbon fibers with theplurality of polymeric staple fibers to form a fiber blend comprisesstack blending.

In accordance with certain embodiments of the invention, the process mayfurther comprise layering a homogenous web (e.g., a first homogenous webor at least a first homogenous web from the one or more homogenous webs)upon itself in a machine direction to form a parallel-laid batt andfixing the parallel-laid batt to form the fiber-reinforced nonwoven. Incertain embodiments of the invention, the molding step may comprisemolding the fiber-reinforced nonwoven to form the fiber-reinforcednonwoven composite. In some embodiments of the invention, fixing theparallel-laid batt may comprise at least one of needle punching orthermal processing. According to certain embodiments of the invention,needle punching may comprise utilizing a needle penetration depth fromabout 5 mm to about 9 mm, from about 7 mm to about 10 mm according tocertain other embodiments of the invention, or from about 10 mm to about75 mm according to yet certain other embodiments of the invention. Inother embodiments of the invention, needle punching may compriseutilizing a needle penetration depth of about 25 mm. In some embodimentof the invention, needle punching may comprise utilizing a punch densityfrom about 50 punches/cm² to about 100 punches/cm². In furtherembodiments of the invention, needle punching may comprise utilizing apunch density of about 75 punches/cm². In some embodiments of theinvention, thermal processing may comprise thermal point bonding.According to certain embodiments of the invention, molding thefiber-reinforced nonwoven to form the fiber-reinforced nonwovencomposite may comprise a molding temperature from about 150° C. to about300° C., from about 200° C. to about 300° C. or from about 200° C. toabout 400° C. In other embodiments of the invention, molding thefiber-reinforced nonwoven to form the fiber-reinforced nonwovencomposite may comprise a molding temperature from about 225° C. to about275° C. In further embodiments of the invention, molding thefiber-reinforced nonwoven to form the fiber-reinforced nonwovencomposite may comprise a molding temperature of about 260° C. In someembodiments of the invention, molding the fiber-reinforced nonwoven toform the fiber-reinforced nonwoven composite may comprise hotcompression molding.

In accordance with certain embodiments of the invention, the pluralityof carbon fibers may comprise staple fibers. In some embodiments of theinvention, the plurality of carbon fibers may be uncrimped. In certainembodiments of the invention, the plurality of carbon fibers maycomprise an average length from about 60 mm to about 100 mm. In furtherembodiments of the invention, the plurality of carbon fibers maycomprise an average length from about 65 mm to about 85 mm. In someembodiments of the invention, the plurality of carbon fibers maycomprise an average length of about 75 mm.

According to certain embodiments of the invention, the plurality ofcarbon fibers may comprise a linear mass density from about 0.1 dtex toabout 1.0 dtex. In other embodiments of the invention, the plurality ofcarbon fibers may comprise a linear mass density from about 0.5 dtex toabout 1.0 dtex. In further embodiments of the invention, the pluralityof carbon fibers may comprise a linear mass density of about 0.7 dtex.

In accordance with certain embodiments of the invention, the polymermatrix may comprise a plurality of polymeric staple fibers. In someembodiments of the invention, the plurality of polymeric staple fibersmay comprise at least one of a thermoplastic polymer or a thermosetpolymer. According to certain embodiments of the invention, theplurality of polymeric staple fibers may comprise at least one of apolyester, a polycarbonate, a co-polyester, a polyamide, a polyphenylenesulfone, an engineering polymer, or any combination thereof. In someembodiments of the invention, the plurality of polymeric staple fibersmay comprise a polyester. In further embodiments of the invention, theplurality of polymeric staple fibers may comprise polyethyleneterephthalate. In certain embodiments of the invention, the plurality ofpolymeric staple fibers may comprise bicomponent fibers.

According to certain embodiments of the invention, the plurality ofpolymeric staple fibers may comprise an average length from about 1 mmto about 100 mm. In other embodiments of the invention, the plurality ofpolymeric staple fibers may comprise an average length from about 1 mmto about 50 mm. In further embodiments of the invention, the pluralityof polymeric staple fibers may comprise an average length of about 38mm.

According to certain embodiments of the invention, the plurality ofpolymeric staple fibers may comprise a linear mass density from about1.0 dtex to about 3.0 dtex. In other embodiments of the invention, theplurality of polymeric staple fibers may comprise a linear mass densityfrom about 1.3 dtex to about 1.8 dtex. In further embodiments of theinvention, the plurality of polymeric staple fibers may comprise alinear mass density of about 1.6 dtex.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a basis weight fromabout 100 gsm to about 5000 gsm or from about 1000 gsm to about 5000gsm. In other embodiments of the invention, the fiber-reinforcednonwoven composite may comprise a basis weight from about 1500 gsm toabout 4000 gsm. In further embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a basis weight fromabout 2000 gsm to about 3000 gsm. In some embodiments of the invention,the fiber-reinforced nonwoven composite may comprise a basis weight ofabout 2500 gsm.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise an average thicknessfrom about 1 mm to about 5 mm. In further embodiments of the invention,the fiber-reinforced nonwoven composite may comprise an averagethickness of about 1.75 mm. According to certain embodiments of theinvention, the fiber-reinforced nonwoven composite may comprise acomposite density from about 1 g/cm³ to about 5 g/cm³. In otherembodiments of the invention, the fiber-reinforced nonwoven compositemay comprise a composite density from about 1 g/cm³ to about 2 g/cm³. Infurther embodiments of the invention, the fiber-reinforced nonwovencomposite may comprise a composite density from about 1.3 g/cm³ to about1.5 g/cm³.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 10 wt. % toabout 100 wt. % carbon fiber and from about 0 wt. % to about 90 wt. %polymer matrix. In other embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 10 wt. % toabout 90 wt. % carbon fiber and from about 10 wt. % to about 90 wt. %polymer matrix. In further embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 10 wt. % toabout 60 wt. % carbon fiber and from about 40 wt. % to about 90 wt. %polymer matrix. According to certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 20 wt. % toabout 50 wt. % carbon fiber and from about 50 wt. % to about 80 wt. %polymer matrix. In some embodiments of the invention, thefiber-reinforced nonwoven composite may comprise from about 30 wt. % toabout 40 wt. % carbon fiber and from about 60 wt. % to about 70 wt. %polymer matrix.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a theoretical voidvolume from about −10% to about 15%. According to certain embodiments ofthe invention, the fiber-reinforced nonwoven composite may comprise atheoretical void volume from about 0% to about 7%. In some embodimentsof the invention, the fiber-reinforced nonwoven composite may comprise atheoretical void volume from about 0% to about 5%.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a plurality ofhomogenous webs having a [0/90] lay-up. In some embodiments of theinvention, the fiber-reinforced nonwoven composite may comprise about 40wt. % carbon fiber and about 60 wt. % thermoplastic polymer matrix. Insuch embodiments of the invention, the fiber-reinforced nonwovencomposite may comprise a tensile modulus from about 15 GPa to about 50GPa. Moreover, the fiber-reinforced nonwoven composite may comprise atensile strength from about 140 MPa to about 600 MPa. In addition, thefiber-reinforced nonwoven composite may comprise a flexural modulus fromabout 15 GPa to about 50 GPa. Furthermore, the fiber-reinforced nonwovencomposite may comprise a flexural strength from about 290 MPa to about465 MPa. In other embodiments of the invention, the fiber-reinforcednonwoven composite may comprise about 30 wt. % carbon fiber and about 70wt. % thermoplastic polymer matrix. In such embodiments of theinvention, the fiber-reinforced nonwoven composite may comprise atensile modulus from about 15 GPa to about 30 GPa. Moreover, thefiber-reinforced nonwoven composite may comprise a tensile strength fromabout 220 MPa to about 310 MPa. In addition, the fiber-reinforcednonwoven composite may comprise a flexural modulus from about 10 GPa toabout 25 GPa. Furthermore, the fiber-reinforced nonwoven composite maycomprise a flexural strength from about 315 MPa to about 385 MPa.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may further comprise an epoxy resin.According to certain embodiments of the invention, the fiber-reinforcednonwoven composite may comprise a structural element utilized in anindustry selected from the group consisting of leisure goods, aerospace,electronics, equipment, energy generation, mass transport, automotiveparts, marine, construction, defense, and sports.

BRIEF DESCRIPTION OF THE DRAWING(S)

The invention now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, this invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout, andwherein:

FIG. 1A is a high compression edge view of a fiber-reinforced nonwovencomposite according to an embodiment of the invention;

FIG. 1B is a low compression edge view of the fiber-reinforced nonwovencomposite of FIG. 1A;

FIG. 2 illustrates a block diagram of a process for forming afiber-reinforced nonwoven composite according to an embodiment of theinvention;

FIG. 3 illustrates a block diagram of a process for forming afiber-reinforced nonwoven according to an embodiment of the invention;

FIG. 4 illustrates the impact of carbon fiber length and theoreticalvoid volume on tensile strength according to an embodiment of theinvention; and

FIG. 5 illustrates the impact of carbon fiber length and theoreticalvoid volume on tensile modulus according to an embodiment of theinvention.

DETAILED DESCRIPTION

The invention now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, this invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. As used in the specification, and in the appended claims,the singular forms “a”, “an”, “the”, include plural referents unless thecontext clearly dictates otherwise.

The invention includes, according to certain embodiments,fiber-reinforced nonwoven composites having a wide variety of uses(e.g., leisure goods, aerospace, electronics, equipment, energygeneration, mass transport, automotive parts, marine, construction,defense, sports and/or the like). The fiber-reinforced nonwovencomposite includes a plurality of reinforcement fibers (e.g., carbonfibers) and a polymer matrix. The plurality of carbon fibers maycomprise an average fiber length from about 50 mm to about 125 mm. Thefiber-reinforced nonwoven composite may comprise a theoretical voidvolume from about 0% to about 10%. In this regard, a fiber-reinforcednonwoven can be consolidated by molding the nonwoven into a thin part(e.g., a fiber-reinforced nonwoven composite) in such a way as achieveboth a high flexural strength and a low void volume.

I. Definitions

The terms “polymer” or “polymeric”, as used interchangeably herein, maycomprise homopolymers, copolymers, such as, for example, block, graft,random, and alternating copolymers, terpolymers, etc., and blends andmodifications thereof. Furthermore, unless otherwise specificallylimited, the term “polymer” or “polymeric” shall include all possiblestructural isomers; stereoisomers including, without limitation,geometric isomers, optical isomers or enantionmers; and/or any chiralmolecular configuration of such polymer or polymeric material. Theseconfigurations include, but are not limited to, isotactic, syndiotactic,and atactic configurations of such polymer or polymeric material.

The terms “nonwoven” and “nonwoven web”, as used herein, may comprise aweb having a structure of individual fibers, filaments, and/or threadsthat are interlaid but not in an identifiable repeating manner as in aknitted or woven fabric. Nonwoven fabrics or webs, according to certainembodiments of the invention, may be formed by any processconventionally known in the art such as, for example, meltblowingprocesses, spunbonding processes, hydroentangling, air-laid, and bondedcarded web processes.

The term “layer”, as used herein, may comprise a generally recognizablecombination of similar material types and/or functions existing in theX-Y plane.

The term “bicomponent fibers”, as used herein, may comprise fibersformed from at least two different polymers extruded from separateextruders but spun together to form one fiber. Bicomponent fibers arealso sometimes referred to as conjugate fibers or multicomponent fibers.The polymers are arranged in a substantially well-defined position indistinct zones across the cross-section of the bicomponent fibers andextend continuously along the length of the bicomponent fibers. Theconfiguration of such a bicomponent fiber may be, for example, asheath/core arrangement wherein one polymer is surrounded by another, ormay be a side-by-side arrangement, a pie arrangement, or an“islands-in-the-sea” arrangement, each as is known in the art ofmulticomponent, including bicomponent, fibers. The “bicomponent fibers”may be thermoplastic fibers that comprise a core fiber made from onepolymer that is encased within a thermoplastic sheath made from adifferent polymer or have a side-by-side arrangement of differentthermoplastic fibers. The first polymer often melts at a different,typically lower, temperature than the second polymer. In the sheath/corearrangement, these bicomponent fibers provide thermal bonding due tomelting of the sheath polymer, while retaining the desirable strengthcharacteristics of the core polymer. In the side-by-side arrangement,the fibers shrink and crimp creating z-direction expansion.

The term “composite”, as used herein, may be a structure comprising twoor more layers, such as a film layer and a fiber layer or a plurality offiber layers molded together. The layers of a composite structure may bejoined together such that a substantial portion of their common X-Yplane interface, according to certain embodiments of the invention.

The term “theoretical void volume”, as used herein, may generally referto the difference between the volume of a part section and the volumetheoretically occupied by components forming the part section. Thisdifference is expressed as a percentage of the volume of the partsection. To determine the theoretical void volume, an estimate of thematrix fiber density Dm (g/cm³), the density of the carbon fiber Dc(g/cm³), the percentage of each of the matrix fiber Vm and the carbonfiber Vc in the composite, the volume of a part section sample Vt (cm³),and the weight of that part Wp (g) are required.

First the average density Da of the component is calculated:Da=[Dm*Vm+Dc*Vc]/100  (1)

The void volume Vv is the difference between the theoretical volume ofthe part Vt (calculated based on its weight Wp and estimated averagedensity Da) and the actual volume Va of the part expressed as apercentage of the actual volume of the part Va.Vv=[(Va−Vt)/Va]*100  (2)Where:Vt=(Wp/Da)  (3)

Va for a flat panel is calculated for a coupon based on the width W(cm), length L (cm), thickness T (cm), and the weight of the coupon Wc(g).Va=Wc*(W*L*T)  (4)

For different shapes, different equations may be used following the sameprinciples.

The term “composite tensile strength”, as used herein, may generallyrefer to the sum of the tensile strength measured in the machinedirection and the tensile strength measured in the cross direction.

II. Fiber-Reinforced Nonwoven Composite

Certain embodiments according to the invention provide fiber-reinforcednonwoven composites suitable for a wide variety of applications (e.g.,leisure goods, aerospace, electronics, equipment, energy generation,mass transport, automotive parts, marine, construction, defense, sportsand/or the like). In one aspect, the fiber-reinforced nonwoven compositeincludes a plurality of carbon fibers and a polymer matrix. Theplurality of reinforcement fibers (e.g., carbon fibers) may have anaverage fiber length from about 50 mm to about 125 mm. To form thefiber-reinforced nonwoven composite, one or more fiber-reinforcednonwoven webs may be cross-lapped in a variety of configurations andthen may be subjected to a molding operation. The one or morefiber-reinforced nonwoven webs nonwovens that may be used in the moldingoperation may be formed by carding a blend comprising thermoplasticfibers (i.e. matrix fibers) and reinforcement fibers where the matrixthermoplastic fibers have a melting point substantially lower than themelting or degradation temperature for the reinforcement fibers. In thisregard, the fiber-reinforced nonwoven composite may comprise atheoretical void volume from about 0% to about 10%. FIGS. 1A and 1B, forinstance, illustrate high and low compression edge views respectively ofa fiber-reinforced nonwoven composite according to an exampleembodiment. FIG. 1A shows areas of fusion, where the matrix fibers havebeen melted and consolidated to form a continuous matrix. FIG. 1B showsreinforcing fibers in aligned configurations surrounded by a meltedand/or fused matrix.

A. Reinforcement Fibers (e.g., Carbon Fibers)

In accordance with certain embodiments of the invention, for instance,the plurality of reinforcement fibers (e.g., carbon fibers) may comprisestaple fibers. In some embodiments of the invention, for example, theplurality of carbon fibers may be uncrimped.

According to certain embodiments of the invention, for instance, theplurality of carbon fibers may comprise an average length from about 50mm to about 125 mm. In other embodiments of the invention, for example,the plurality of carbon fibers may comprise an average length from about60 mm to about 100 mm. In further embodiments of the invention, forinstance, the plurality of carbon fibers may comprise an average lengthfrom about 65 mm to about 85 mm. In some embodiments of the invention,for example, the plurality of carbon fibers may comprise an averagelength of about 75 mm. As such, in certain embodiments of the invention,the plurality of carbon fibers may comprise an average length from atleast about any of the following: 50, 55, 60, 65, 70, and 75 mm and/orat most about 125, 100, 95, 90, 85, 80, and 75 mm (e.g., about 50-80 mm,about 75-100 mm, etc.).

According to certain embodiments of the invention, for instance, theplurality of carbon fibers may comprise a linear mass density from about0.1 dtex to about 1.0 dtex. In other embodiments of the invention, forexample, the plurality of carbon fibers may comprise a linear massdensity from about 0.5 dtex to about 1.0 dtex. In further embodiments ofthe invention, for instance, the plurality of carbon fibers may comprisea linear mass density of about 0.7 dtex. As such, in certain embodimentsof the invention, the plurality of carbon fibers may comprise a linearmass density from at least about any of the following: 0.1, 0.2, 0.3,0.4, 0.5, 0.6, and 0.7 dtex and/or at most about 1.0, 0.9, 0.8, and 0.7dtex (e.g., about 0.3-0.7 dtex, about 0.5-1.0 dtex, etc.).

B. Polymer Matrix

In accordance with certain embodiments of the invention, for example,the polymer matrix may comprise a plurality of polymeric staple fibers.In some embodiments of the invention, for instance, the plurality ofpolymeric staple fibers may comprise at least one of a thermoplasticpolymer or a thermoset polymer. According to certain embodiments of theinvention, for example, the plurality of polymeric staple fibers maycomprise at least one of a polyester, a polycarbonate, a co-polyester, apolyamide, a polyphenylene sulfone, an engineering polymer, or anycombination thereof. In some embodiments of the invention, for instance,the plurality of polymeric staple fibers may comprise a polyester. Infurther embodiments of the invention, for example, the plurality ofpolymeric staple fibers may comprise polyethylene terephthalate. Incertain embodiments of the invention, for instance, the plurality ofpolymeric staple fibers may comprise bicomponent fibers. In someembodiments of the invention, for example, the plurality of polymericstaple fibers may comprise a substantially lower melting temperaturethan the melting and/or degradation temperature of the carbon fibers.

According to certain embodiments of the invention, for example, theplurality of polymeric staple fibers may comprise an average length fromabout 1 mm to about 100 mm. In other embodiments of the invention, forinstance, the plurality of polymeric staple fibers may comprise anaverage length from about 1 mm to about 50 mm. In further embodiments ofthe invention, for example, the plurality of polymeric staple fibers maycomprise an average length of about 38 mm. As such, in certainembodiments of the invention, the plurality of carbon fibers maycomprise an average length from at least about any of the following: 1,10, 20, 30, 35, and 38 mm and/or at most about 50, 48, 45, 42, 40, and38 mm (e.g., about 20-50 mm, about 35-42 mm, etc.).

According to certain embodiments of the invention, for instance, theplurality of polymeric staple fibers may comprise a linear mass densityfrom about 1.0 dtex to about 3.0 dtex. In other embodiments of theinvention, for example, the plurality of polymeric staple fibers maycomprise a linear mass density from about 1.3 dtex to about 1.8 dtex. Infurther embodiments of the invention, for instance, the plurality ofpolymeric staple fibers may comprise a linear mass density of about 1.6dtex. As such, in certain embodiments of the invention, the plurality ofcarbon fibers may comprise a linear mass density from at least about anyof the following: 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, and 1.6 dtex and/or atmost about 3.0, 2.0, 1.9, 1.8, 1.7, and 1.6 dtex (e.g., about 1.1-1.7dtex, about 1.5-1.7 dtex, etc.).

C. Structure of the Fiber-Reinforced Nonwoven Composite

In accordance with certain embodiments of the invention, a homogenousweb of the carded fiber blend of reinforcement fibers (e.g., carbonfibers) and polymer matrix fibers may be layered upon itself, forexample in a machine direction (e.g., the longest dimension of thehomogenous web), in a parallel configuration to form a parallel-laidbatt. The formed parallel-laid batt may be fixed, such as byneedle-punching, to form a fiber-reinforced nonwoven. Thefiber-reinforced nonwoven may be subjected to a molding operation toform a fiber-reinforced nonwoven composite according to certainembodiments of the invention. In accordance with certain embodiments ofthe invention, the homogenous web may be fixed, such as byneedle-punching, prior to being layered upon itself, for example in amachine direction (e.g., the longest dimension of the homogenous web) ina parallel configuration as discussed above.

In accordance with certain embodiments of the invention, a plurality ofindividual homogenous webs of the carded fiber blend of carbon fibersand polymer matrix fibers may be laid-up in a variety of differentconfigurations (e.g., lay-up orientations). For example, the pluralityof individual homogenous webs may be subjected to a variety of lay-uporientations relative to each other (e.g., parallel-laid,orthogonally-laid, etc.). Each of the homogenous webs may beindependently laid relative to adjacent homogenous webs. By way ofexample only, embodiments of the invention may comprise a firsthomogenous web being aligned in a first direction laid directly orindirectly onto or over a second homogenous web being aligned in asecond direction, in which the first direction and the second directionare not the same. For instance, the first direction may be considered tobe at 0° (as a point of reference) and the second direction may comprise90° relative to the first direction (e.g., from between 5-175°, 20-160°,40-140°, 60-120°, 80-100° relative to the first direction). For example,a [0/90] lay-up orientation references a first homogenous web aligned ina direction considered to be at 0° (as a point of reference) and asecond homogenous web laid on top or over the first homogenous web, inwhich the second homogenous web is aligned in direction 90° relative tothe alignment of the first homogenous web. In accordance with certainembodiments, the laid-up homogenous webs may define a fiber batt. Theformed batt may be fixed, such as by needle-punching, to form afiber-reinforced nonwoven. The fiber-reinforced nonwoven may besubjected to a molding operation to form a fiber-reinforced nonwovencomposite according to certain embodiments of the invention. Inaccordance with certain embodiments of the invention, each of thehomogenous webs may be fixed, such as by needle-punching, prior to beinglaid-up in various configurations as discussed above.

In accordance with certain embodiments of the invention, for example,the fiber-reinforced nonwoven composite may comprise a basis weight fromabout 1000 gsm to about 5000 gsm. In other embodiments of the invention,for instance, the fiber-reinforced nonwoven composite may comprise abasis weight from about 1500 gsm to about 4000 gsm. In furtherembodiments of the invention, for example, the fiber-reinforced nonwovencomposite may comprise a basis weight from about 2000 gsm to about 3000gsm. In some embodiments of the invention, for instance, thefiber-reinforced nonwoven composite may comprise a basis weight of about2500 gsm. As such, in certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a basis weight from atleast about any of the following: 1000, 1500, 2000, and 2500 gsm and/orat most about 5000, 4500, 4000, 3500, 3000, and 2500 gsm (e.g., about1000-4000 gsm, about 2000-3000 gsm, etc.).

In accordance with certain embodiments of the invention, for example,the fiber-reinforced nonwoven composite may comprise an averagethickness from about 1 mm to about 3 mm. In further embodiments of theinvention, for instance, the fiber-reinforced nonwoven composite maycomprise an average thickness of about 1.75 mm. As such, in certainembodiments of the invention, the fiber-reinforced nonwoven compositemay comprise an average thickness from at least about any of thefollowing: 1, 1.25, 1.5, and 1.75 mm and/or at most about 3, 2.75, 2.5,2.25, 2, and 1.75 mm (e.g., about 1.5-3 mm, about 1-2 mm, etc.).

According to certain embodiments of the invention, for example, thefiber-reinforced nonwoven composite may comprise a composite densityfrom about 1 g/cm³ to about 5 g/cm³. In other embodiments of theinvention, for instance, the fiber-reinforced nonwoven composite maycomprise a composite density from about 1 g/cm³ to about 2 g/cm³. Infurther embodiments of the invention, for example, the fiber-reinforcednonwoven composite may comprise a composite density from about 1.3 g/cm³to about 1.5 g/cm³. As such, in certain embodiments of the invention,the fiber-reinforced nonwoven composite may comprise a composite densityfrom at least about any of the following: 1, 1.1, 1.2, and 1.3 g/cm³and/or at most about 5, 4, 3, 2, and 1.5 g/cm³ (e.g., about 1.1-1.5g/cm³, about 1.3-5 g/cm³, etc.).

In accordance with certain embodiments of the invention, for instance,the fiber-reinforced nonwoven composite may comprise from about 10 wt. %to about 100 wt. % carbon fiber and from about 0 wt. % to about 90 wt. %polymer matrix. In other embodiments of the invention, for example, thefiber-reinforced nonwoven composite may comprise from about 10 wt. % toabout 90 wt. % carbon fiber and from about 10 wt. % to about 90 wt. %polymer matrix. In further embodiments of the invention, for instance,the fiber-reinforced nonwoven composite may comprise from about 10 wt. %to about 60 wt. % carbon fiber and from about 40 wt. % to about 90 wt. %polymer matrix. According to certain embodiments of the invention, forexample, the fiber-reinforced nonwoven composite may comprise from about20 wt. % to about 50 wt. % carbon fiber and from about 50 wt. % to about80 wt. % polymer matrix. In some embodiments of the invention, forinstance, the fiber-reinforced nonwoven composite may comprise fromabout 30 wt. % to about 40 wt. % carbon fiber and from about 60 wt. % toabout 70 wt. % polymer matrix. As such, in certain embodiments of theinvention, the fiber-reinforced nonwoven composite may comprise a weightpercentage of carbon fiber from at least about any of the following: 10,15, 20, 25, and 30 wt. % and/or at most about 100, 90, 60, 50, and 40wt. % (e.g., about 30-50 wt. %, about 25-60 wt. %, etc.). Moreover, incertain embodiments of the invention, the fiber-reinforced nonwovencomposite may comprise a weight percentage of polymer matrix from atleast about any of the following: 0, 5, 10, 20, 30, 40, 50, and 60 wt. %and/or at most about 90, 85, 80, 75, and 70 wt. % (e.g., about 40-80 wt.%, about 60-90 wt. %, etc.).

In accordance with certain embodiments of the invention, for example,the fiber-reinforced nonwoven composite may comprise a theoretical voidvolume from about −10% to about 15%. According to certain embodiments ofthe invention, for instance, the fiber-reinforced nonwoven composite maycomprise a theoretical void volume from about 0% to about 10%. In someembodiments of the invention, for example, the fiber-reinforced nonwovencomposite may comprise a theoretical void volume from about 0% to about7%. In further embodiments of the invention, for instance, thefiber-reinforced nonwoven composite may comprise a theoretical voidvolume from about 0% to about 5%. In other embodiments of the invention,for example, the fiber-reinforced nonwoven composite may comprise atheoretical void volume from about 0% to about 1%. As such, in certainembodiments of the invention, the fiber-reinforced nonwoven compositemay comprise a theoretical void volume from at least about any of thefollowing: −10, −9, −8, −7, −6, −5, −4, −3, −2, −1, and 0% and/or atmost about 15, 12, 10, 9, 8, 7, 6, 5, 4, 3, 2, and 1% (e.g., about0-12%, about 0-5%, etc.).

In accordance with certain embodiments of the invention, for instance,the fiber-reinforced nonwoven composite may comprise a [0/90] lay-up. Insome embodiments of the invention, for example, the fiber-reinforcednonwoven composite may comprise about 40 wt. % carbon fiber and about 60wt. % thermoplastic polymer matrix. In such embodiments of theinvention, for instance, the fiber-reinforced nonwoven composite maycomprise a tensile modulus from about 15 GPa to about 50 GPa. Moreover,for example, the fiber-reinforced nonwoven composite may comprise atensile strength from about 140 MPa to about 600 MPa. In addition, forinstance, the fiber-reinforced nonwoven composite may comprise aflexural modulus from about 15 GPa to about 50 GPa. Furthermore, forexample, the fiber-reinforced nonwoven composite may comprise a flexuralstrength from about 290 MPa to about 465 MPa.

In other embodiments of the invention, for instance, thefiber-reinforced nonwoven composite may comprise a [0/90] lay-up, about30 wt. % carbon fiber, and about 70 wt. % thermoplastic polymer matrix.In such embodiments of the invention, for example, the fiber-reinforcednonwoven composite may comprise a tensile modulus from about 15 GPa toabout 30 GPa. Moreover, for instance, the fiber-reinforced nonwovencomposite may comprise a tensile strength from about 220 MPa to about310 MPa. In addition, for example, the fiber-reinforced nonwovencomposite may comprise a flexural modulus from about 10 GPa to about 25GPa. Furthermore, for instance, the fiber-reinforced nonwoven compositemay comprise a flexural strength from about 315 MPa to about 385 MPa.

In accordance with certain embodiments of the invention, for example,the fiber-reinforced nonwoven composite may further comprise an epoxyresin. According to certain embodiments of the invention, for instance,the fiber-reinforced nonwoven composite may comprise a structuralelement utilized in an industry selected from the group consisting ofleisure goods, aerospace, electronics, equipment, energy generation,mass transport, automotive parts, marine, construction, defense, andsports.

III. Process for Forming a Fiber-Reinforced Nonwoven Composite

In another aspect, certain embodiments of the invention provide aprocess for forming a fiber-reinforced nonwoven composite. The processincludes opening a plurality of reinforcement fibers (e.g., carbonfibers) and a plurality of polymeric staple fibers, blending theplurality of carbon fibers with the plurality of polymeric staple fibersto form a fiber blend, carding the fiber blend to form one or morehomogenous webs, forming a fiber-reinforced nonwoven from the one ormore homogenous webs, and molding the fiber-reinforced nonwoven to forma fiber-reinforced nonwoven composite. The plurality of carbon fibersmay have an average fiber length from about 50 mm to about 125 mm.Moreover, the fiber-reinforced nonwoven composite may comprise atheoretical void volume from about 0% to about 10%.

According to certain embodiments of the invention, for example, blendingthe plurality of carbon fibers with the plurality of polymeric staplefibers to form a fiber blend comprises stack blending. Moreover, inaccordance with certain embodiments of the invention, for instance, theprocess may further comprise layering a homogenous web upon itself in amachine direction or a cross direction to form a parallel-laid batt andfixing the parallel-laid batt to form the fiber-reinforced nonwoven. Insome embodiments of the invention, for example, the molding step maycomprise molding the fiber-reinforced nonwoven to form thefiber-reinforced nonwoven composite.

FIG. 2, for example, illustrates a block diagram of a process forforming a fiber-reinforced nonwoven composite according to an embodimentof the invention. As shown in FIG. 2, for instance, the process includesopening a plurality of carbon fibers and a plurality of polymeric staplefibers at operation 210, blending the plurality of carbon fibers withthe plurality of polymeric staple fibers to form a fiber blend atoperation 220, carding the fiber blend to form one or more homogenouswebs at operation 230, forming a fiber-reinforced nonwoven from the oneor more homogenous webs at operation 240, and molding thefiber-reinforced nonwoven to form a fiber-reinforced nonwoven compositeat operation 250. Moreover, FIG. 3, for instance, illustrates a blockdiagram of a process for forming a fiber-reinforced nonwoven accordingto an embodiment of the invention. As shown in FIG. 3, for example, theprocess includes layering a homogenous web upon itself in a machinedirection to form a parallel-laid batt at operation 310, fixing theparallel-laid batt to form the fiber-reinforced nonwoven at operation320, and molding the fiber-reinforced nonwoven to form thefiber-reinforced nonwoven composite at operation 330.

In some embodiments of the invention, for example, fixing theparallel-laid batt may comprise at least one of needle punching orthermal processing. According to certain embodiments of the invention,for instance, needle punching may comprise utilizing a needlepenetration depth from about 5 mm to about 9 mm, from about 7 mm toabout 10 mm according to certain other embodiments of the invention, orfrom about 10 mm to about 75 mm according to yet certain otherembodiments of the invention. In other embodiments of the invention, forexample, needle punching may comprise utilizing a needle penetrationdepth of about 7 mm or about 25 mm according to certain otherembodiments of the invention. As such, in certain embodiments of theinvention, needle punching may comprise utilizing a needle penetrationdepth from at least about any of the following: 5, 5.5, 6, 6.5, and 7 mmand/or at most about 75, 50, 25, 15, 10, 9, 8.5, 8, 7.5, and 7 mm (e.g.,about 5.5-75 mm, about 6.5-25 mm, etc.). The needle penetration depthmay be from about 7 mm to about 10 mm according to certain otherembodiments of the invention or from about 10 mm to about 75 mmaccording to yet certain other embodiments of the invention.

In some embodiment of the invention, for example, needle punching maycomprise utilizing a punch density from about 50 punches/cm² to about100 punches/cm². In further embodiments of the invention, for instance,needle punching may comprise utilizing a punch density of about 75punches/cm². As such, in certain embodiments of the invention, needlepunching may comprise utilizing a punch density from at least about anyof the following: 50, 55, 60, 65, 70, and 75 punches/cm² and/or at mostabout 100, 95, 90, 85, 80, and 75 punches/cm² (e.g., about 60-85punches/cm², about 75-80 punches/cm², etc.).

In some embodiments of the invention, for example, thermal processingmay comprise thermal point bonding. Thermal point bonding can beaccomplished by passing the parallel-laid batt through a pressure nipformed by two rolls, one of which is heated and contains a plurality ofraised protrusions having one or more geometric shapes (e.g., points,diamond shaped, circular, elliptical, dog-bone shaped, etc.) on itssurface which impart or form corresponding discrete thermal bond siteson the fibrous web.

In accordance with certain embodiments of the invention, a plurality ofindividual homogenous webs of the carded fiber blend of carbon fibersand polymer matrix fibers may be laid-up in a variety of differentconfigurations (e.g., lay-up orientations). For example, the pluralityof individual homogenous webs may be subjected to a variety of lay-uporientations relative to each other (e.g., parallel-laid,orthogonally-laid, etc.). Each of the homogenous webs may beindependently laid relative to adjacent homogenous webs. By way ofexample only, embodiments of the invention may comprise a firsthomogenous web being aligned in a first direction laid directly orindirectly onto or over a second homogenous web being aligned in asecond direction, in which the first direction and the second directionare not the same. For instance, the first direction may be considered tobe at 0° (as a point of reference) and the second direction may comprise90° relative to the first direction (e.g., from between 5-175°, 20-160°,40-1400, 60-1200, 80-100° relative to the first direction). For example,a [0/90] lay-up orientation references a first homogenous web aligned ina direction considered to be at 0° (as a point of reference) and asecond homogenous web laid on top or over the first homogenous web, inwhich the second homogenous web is aligned in direction 90° relative tothe alignment of the first homogenous web. In accordance to certainembodiments, the laid-up homogenous webs may define fiber batt. Theformed batt may be fixed, such as by needle-punching, to form afiber-reinforced nonwoven. The fiber-reinforced nonwoven may besubjected to a molding operation to form a fiber-reinforced nonwovencomposite according to certain embodiments of the invention. Inaccordance with certain embodiments of the invention, each of thehomogenous webs may be fixed, such as by needle-punching, prior to beinglaid-up in various configurations as discussed above.

In some embodiments including a plurality of individual homogenous webslaid-up in a variety of different configurations may define a fiberbatt, which may be fixed by at least one of needle punching or thermalprocessing. According to certain embodiments of the invention, forinstance, needle punching may comprise utilizing a needle penetrationdepth from about 5 mm to about 9 mm or from about 7 mm to about 10 mmaccording to certain other embodiments of the invention. In otherembodiments of the invention, for example, needle punching may compriseutilizing a needle penetration depth of about 7 mm. As such, in certainembodiments of the invention, needle punching may comprise utilizing aneedle penetration depth from at least about any of the following: 5,5.5, 6, 6.5, and 7 mm and/or at most about 75, 50, 25, 15, 10, 9, 8.5,8, 7.5, and 7 mm (e.g., about 5.5-75 mm, about 6.5-25 mm, etc.). Theneedle penetration depth may be from about 7 mm to about 10 mm accordingto certain other embodiments of the invention or from about 10 mm toabout 75 mm according to yet certain other embodiments of the invention.

In some embodiment of the invention, for example, needle punching maycomprise utilizing a punch density from about 50 punches/cm² to about100 punches/cm². In further embodiments of the invention, for instance,needle punching may comprise utilizing a punch density of about 75punches/cm². As such, in certain embodiments of the invention, needlepunching may comprise utilizing a punch density from at least about anyof the following: 50, 55, 60, 65, 70, and 75 punches/cm² and/or at mostabout 100, 95, 90, 85, 80, and 75 punches/cm² (e.g., about 60-85punches/cm², about 75-80 punches/cm², etc.).

In some embodiments of the invention, for example, thermal processingmay comprise thermal point bonding. Thermal point bonding can beaccomplished by passing the fiber batt of the plurality of individuallylaid-up homogenous webs through a pressure nip formed by two rolls, oneof which is heated and contains a plurality of raised protrusions havingone or more geometric shapes (e.g., points, diamond shaped, circular,elliptical, dog-bone shaped, etc.) on its surface which impart or formcorresponding discrete thermal bond sites on the fibrous web.

According to certain embodiments of the invention, for instance, moldingthe fiber-reinforced nonwoven to form the fiber-reinforced nonwovencomposite may comprise a molding temperature from about 200° C. to about300° C. In other embodiments of the invention, for example, molding thefiber-reinforced nonwoven to form the fiber-reinforced nonwovencomposite may comprise a molding temperature from about 225° C. to about275° C. In further embodiments of the invention, for instance, moldingthe fiber-reinforced nonwoven to form the fiber-reinforced nonwovencomposite may comprise a molding temperature of about 260° C. As such,in certain embodiments, molding the fiber-reinforced nonwoven to formthe fiber-reinforced nonwoven composite may comprise a moldingtemperature from at least about any of the following: 200, 225, 230,240, 250, and 260° C. and/or at most about 300, 290, 280, 275, 270, and260° C. (e.g., about 250-270° C., about 260-300° C., etc.).

In some embodiments of the invention, for example, molding thefiber-reinforced nonwoven to form the fiber-reinforced nonwovencomposite may comprise hot compression molding. Hot compression moldingmay be accomplished by placing the fiber-reinforced nonwoven in an open,heated mold cavity. The mold may then be closed with a top force or plugmember, pressure may be applied to force the material into contact withall mold areas, and heat and pressure may be maintained until thefiber-reinforced nonwoven composite has cured. In this regard, thefiber-reinforced nonwoven may be placed directly into a heated metalmold, then softened by the heat, and forced to conform to the shape ofthe mold as the mold closes to form the fiber-reinforced nonwovencomposite.

In accordance with certain embodiments of the invention, for instance,the plurality of reinforcement fibers (e.g., carbon fibers) may comprisestaple fibers. In some embodiments of the invention, for example, theplurality of carbon fibers may be uncrimped.

According to certain embodiments of the invention, for instance, theplurality of carbon fibers may comprise an average length from about 50mm to about 125 mm. In other embodiments of the invention, for example,the plurality of carbon fibers may comprise an average length from about60 mm to about 100 mm. In further embodiments of the invention, forinstance, the plurality of carbon fibers may comprise an average lengthfrom about 65 mm to about 85 mm. In some embodiments of the invention,for example, the plurality of carbon fibers may comprise an averagelength of about 75 mm. As such, in certain embodiments of the invention,the plurality of carbon fibers may comprise an average length from atleast about any of the following: 50, 55, 60, 65, 70, and 75 mm and/orat most about 125, 100, 95, 90, 85, 80, and 75 mm (e.g., about 50-80 mm,about 75-100 mm, etc.).

According to certain embodiments of the invention, for instance, theplurality of carbon fibers may comprise a linear mass density from about0.1 dtex to about 1.0 dtex. In other embodiments of the invention, forexample, the plurality of carbon fibers may comprise a linear massdensity from about 0.5 dtex to about 1.0 dtex. In further embodiments ofthe invention, for instance, the plurality of carbon fibers may comprisea linear mass density of about 0.7 dtex. As such, in certain embodimentsof the invention, the plurality of carbon fibers may comprise a linearmass density from at least about any of the following: 0.1, 0.2, 0.3,0.4, 0.5, 0.6, and 0.7 dtex and/or at most about 1.0, 0.9, 0.8, and 0.7dtex (e.g., about 0.3-0.9 dtex, about 0.5-1.0 dtex, etc.).

In accordance with certain embodiments of the invention, for example,the polymer matrix may comprise a plurality of polymeric staple fibers.In some embodiments of the invention, for instance, the plurality ofpolymeric staple fibers may comprise at least one of a thermoplasticpolymer or a thermoset polymer. According to certain embodiments of theinvention, for example, the plurality of polymeric staple fibers maycomprise at least one of a polyester, a polycarbonate, a co-polyester, apolyamide, a polyphenylene sulfone, an engineering polymer, or anycombination thereof. In some embodiments of the invention, for instance,the plurality of polymeric staple fibers may comprise a polyester. Infurther embodiments of the invention, for example, the plurality ofpolymeric staple fibers may comprise polyethylene terephthalate. Incertain embodiments of the invention, for instance, the plurality ofpolymeric staple fibers may comprise bicomponent fibers.

According to certain embodiments of the invention, for example, theplurality of polymeric staple fibers may comprise an average length fromabout 1 mm to about 100 mm. In other embodiments of the invention, forinstance, the plurality of polymeric staple fibers may comprise anaverage length from about 1 mm to about 50 mm. In further embodiments ofthe invention, for example, the plurality of polymeric staple fibers maycomprise an average length of about 38 mm. As such, in certainembodiments of the invention, the plurality of carbon fibers maycomprise an average length from at least about any of the following: 1,10, 20, 30, 35, and 38 mm and/or at most about 50, 48, 45, 42, 40, and38 mm (e.g., about 20-50 mm, about 35-42 mm, etc.).

According to certain embodiments of the invention, for instance, theplurality of polymeric staple fibers may comprise a linear mass densityfrom about 1.0 dtex to about 3.0 dtex. In other embodiments of theinvention, for example, the plurality of polymeric staple fibers maycomprise a linear mass density from about 1.3 dtex to about 1.8 dtex. Infurther embodiments of the invention, for instance, the plurality ofpolymeric staple fibers may comprise a linear mass density of about 1.6dtex. As such, in certain embodiments of the invention, the plurality ofcarbon fibers may comprise a linear mass density from at least about anyof the following: 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, and 1.6 dtex and/or atmost about 3.0, 2.0, 1.9, 1.8, 1.7, and 1.6 dtex (e.g., about 1.1-1.7dtex, about 1.5-1.7 dtex, etc.).

In this regard, a fiber-reinforced nonwoven composite comprising aplurality of carbon fibers and a polymer matrix may be formed such thatthe plurality of carbon fibers have an average fiber length from about50 mm to about 125 mm, and the fiber-reinforced nonwoven composite maycomprise a theoretical void volume from about 0% to about 10%.

The fiber-reinforced nonwoven composite produced according to certainembodiments of the invention may comprise a basis weight from about 1000gsm to about 5000 gsm. In other embodiments of the invention, forinstance, the fiber-reinforced nonwoven composite may comprise a basisweight from about 1500 gsm to about 4000 gsm. In further embodiments ofthe invention, for example, the fiber-reinforced nonwoven composite maycomprise a basis weight from about 2000 gsm to about 3000 gsm. In someembodiments of the invention, for instance, the fiber-reinforcednonwoven composite may comprise a basis weight of about 2500 gsm. Assuch, in certain embodiments of the invention, the fiber-reinforcednonwoven composite may comprise a basis weight from at least about anyof the following: 1000, 1500, 2000, and 2500 gsm and/or at most about5000, 4500, 4000, 3500, 3000, and 2500 gsm (e.g., about 1000-4000 gsm,about 2000-3000 gsm, etc.).

The fiber-reinforced nonwoven composite produced according to certainembodiments of the invention may comprise an average thickness fromabout 1 mm to about 3 mm. In further embodiments of the invention, forinstance, the fiber-reinforced nonwoven composite may comprise anaverage thickness of about 1.75 mm. As such, in certain embodiments ofthe invention, the fiber-reinforced nonwoven composite may comprise anaverage thickness from at least about any of the following: 1, 1.25,1.5, and 1.75 mm and/or at most about 3, 2.75, 2.5, 2.25, 2, and 1.75 mm(e.g., about 1.5-3 mm, about 1-2 mm, etc.).

The fiber-reinforced nonwoven composite produced according to certainembodiments of the invention may comprise a composite density from about1 g/cm³ to about 5 g/cm³. In other embodiments of the invention, forinstance, the fiber-reinforced nonwoven composite may comprise acomposite density from about 1 g/cm³ to about 2 g/cm³. In furtherembodiments of the invention, for example, the fiber-reinforced nonwovencomposite may comprise a composite density from about 1.3 g/cm³ to about1.5 g/cm³. As such, in certain embodiments of the invention, thefiber-reinforced nonwoven composite may comprise a composite densityfrom at least about any of the following: 1, 1.1, 1.2, and 1.3 g/cm³and/or at most about 5, 4, 3, 2, and 1.5 g/cm³ (e.g., about 1.1-1.5g/cm³, about 1.3-5 g/cm³, etc.).

The fiber-reinforced nonwoven composite produced according to certainembodiments of the invention may comprise from about 10 wt. % to about100 wt. % carbon fiber and from about 0 wt. % to about 90 wt. % polymermatrix. In other embodiments of the invention, for example, thefiber-reinforced nonwoven composite may comprise from about 10 wt. % toabout 90 wt. % carbon fiber and from about 10 wt. % to about 90 wt. %polymer matrix. In further embodiments of the invention, for instance,the fiber-reinforced nonwoven composite may comprise from about 10 wt. %to about 60 wt. % carbon fiber and from about 40 wt. % to about 90 wt. %polymer matrix. According to certain embodiments of the invention, forexample, the fiber-reinforced nonwoven composite may comprise from about20 wt. % to about 50 wt. % carbon fiber and from about 50 wt. % to about80 wt. % polymer matrix. In some embodiments of the invention, forinstance, the fiber-reinforced nonwoven composite may comprise fromabout 30 wt. % to about 40 wt. % carbon fiber and from about 60 wt. % toabout 70 wt. % polymer matrix. As such, in certain embodiments of theinvention, the fiber-reinforced nonwoven composite may comprise a weightpercentage of carbon fiber from at least about any of the following: 10,15, 20, 25, and 30 wt. % and/or at most about 100, 90, 60, 50, and 40wt. % (e.g., about 30-50 wt. %, about 25-60 wt. %, etc.). Moreover, incertain embodiments of the invention, the fiber-reinforced nonwovencomposite may comprise a weight percentage of polymer matrix from atleast about any of the following: 0, 5, 10, 20, 30, 40, 50, and 60 wt. %and/or at most about 90, 85, 80, 75, and 70 wt. % (e.g., about 40-80 wt.%, about 60-90 wt. %, etc.).

The fiber-reinforced nonwoven composite produced according to certainembodiments of the invention may comprise a theoretical void volume fromabout −10% to about 15%. According to certain embodiments of theinvention, for instance, the fiber-reinforced nonwoven composite maycomprise a theoretical void volume from about 0% to about 10%. In someembodiments of the invention, for example, the fiber-reinforced nonwovencomposite may comprise a theoretical void volume from about 0% to about7%. In further embodiments of the invention, for instance, thefiber-reinforced nonwoven composite may comprise a theoretical voidvolume from about 0% to about 5%. In other embodiments of the invention,for example, the fiber-reinforced nonwoven composite may comprise atheoretical void volume from about 0% to about 1%. As such, in certainembodiments of the invention, the fiber-reinforced nonwoven compositemay comprise a theoretical void volume from at least about any of thefollowing: −10, −9, −8, −7, −6, −5, −4, −3, −2, −1, and 0% and/or atmost about 15, 12, 10, 9, 8, 7, 6, 5, 4, 3, 2, and 1% (e.g., about0-12%, about 0-5%, etc.).

In accordance with certain embodiments of the invention, for instance,the fiber-reinforced nonwoven composite may comprise a plurality ofindividual homogenous webs having a [0/90] lay-up. In some embodimentsof the invention, for example, the fiber-reinforced nonwoven compositemay comprise about 40 wt. % carbon fiber and about 60 wt. %thermoplastic polymer matrix. In such embodiments of the invention, forinstance, the fiber-reinforced nonwoven composite may comprise a tensilemodulus from about 15 GPa to about 50 GPa. Moreover, for example, thefiber-reinforced nonwoven composite may comprise a tensile strength fromabout 140 MPa to about 600 MPa. In addition, for instance, thefiber-reinforced nonwoven composite may comprise a flexural modulus fromabout 15 GPa to about 50 GPa. Furthermore, for example, thefiber-reinforced nonwoven composite may comprise a flexural strengthfrom about 290 MPa to about 465 MPa.

In other embodiments of the invention, for instance, thefiber-reinforced nonwoven composite may comprise a plurality ofindividual homogenous webs having a [0/90] lay-up, about 30 wt. % carbonfiber, and about 70 wt. % thermoplastic polymer matrix. In suchembodiments of the invention, for example, the fiber-reinforced nonwovencomposite may comprise a tensile modulus from about 15 GPa to about 30GPa. Moreover, for instance, the fiber-reinforced nonwoven composite maycomprise a tensile strength from about 220 MPa to about 310 MPa. Inaddition, for example, the fiber-reinforced nonwoven composite maycomprise a flexural modulus from about 10 GPa to about 25 GPa.Furthermore, for instance, the fiber-reinforced nonwoven composite maycomprise a flexural strength from about 315 MPa to about 385 MPa.

In accordance with certain embodiments of the invention, thefiber-reinforced nonwoven composite may further comprise an epoxy resin.According to certain embodiments of the invention, the fiber-reinforcednonwoven composite may comprise a structural element utilized in anindustry selected from the group consisting of leisure goods, aerospace,electronics, equipment, energy generation, mass transport, automotiveparts, marine, construction, defense, and sports.

IV. Applications for a Fiber-Reinforced Nonwoven Composite

According to certain embodiments of the invention, the fiber-reinforcednonwoven composite may comprise a structural element utilized in anindustry selected from the group consisting of leisure goods, aerospace,electronics, equipment, energy generation, mass transport, automotiveparts, marine, construction, defense, and sports.

EXAMPLES

The present disclosure is further illustrated by the following examples,which in no way should be construed as being limiting. That is, thespecific features described in the following examples are merelyillustrative and not limiting.

Example 1

Example 1 was made by blending and carding PET fibers from Advansa GmbH,Frielinghauser Str. 5, 59071 Hamm, Germany, (product code is 1.6-38-158NSD Merge 123 E56) with carbon staple fibers from William Barnet & Son,1300 Hayne Street, Spartanburg, S.C. 29301. The PET fibers had a 38 mmcut length and a linear density of 1.62 dtex. The carbon fibers wereabout 6 microns in diameter and had a cut length of 50 mm. The carbonfibers were treated with a similar PET fiber finish as the Advansa PETfibers prior to cutting. The relative content of this example was 60 wt.% PET and 40 wt. % carbon fibers. The web was then cross-lapped andlightly needled into a 500 gsm web to form a consolidated nonwoven.

Five pieces having dimensions of 300 mm×500 mm were cut from thenonwoven on 1 meter wide roll goods into 300 mm×500 mm samples and werelayered, keeping the same orientation as the roll goods, to create a2500 gsm mat that was molded on a hydraulic press equipped with two dieshaving parallel surfaces that can be pressed toward each other while thesample is positioned between them. This press is equipped with a stopthat controls the minimum separation between the plates. For thisexample, the stop created a gap of 2 mm between the parallel plates.

The molding step consisted of first positioning the 5 pieces of nonwovenbetween the parallel plates of the press and applying 220 psi (1.51MPa). Then, heat was also applied to the parallel plates until theyreached a temperature of 260° C. At that point, the pressure applied tothe plate was raised to 1088 psi (7.5 MPa) for approximately 2 minutes,then cooling was applied to the plates, and the pressure was removedwhen the plate temperature was reduced to 40° C.

Using a table saw, coupons were removed in the machine direction (MD)and cross direction (CD) from the formed plates and tested according toDIN EN ISO 527. The examples were produced as per the Type 2requirements of the standard, and each data point is the average of themeasurements made on 5 different coupons (N=5 on each data point).

Example 2

A plate was molded according to Example 1 with the exception that thethickness of the stop was reduced to 1.5 mm.

Example 3

This example was made according to Example 1 with the exception that thecarbon fibers had a length of 75 mm. For this example, the stop for theminimum distance between the plates was the same as Example 1 at 2 mm.

Example 4

This example was made according to Example 3 with the exception that thestop was set at 1.75 mm.

Example 5

This example was made according to Example 3 with the exception that thestop was set at 1.5 mm.

The test results for those samples can be found in Tables 1-3 below.

TABLE 1 Set Carbon minimum Average Calculated MD MD MD fiber gap formeasured void Tensile Tensile tensile length the press thickness volumestrength strain modulus Units mm mm mm % Mpa % Gpa Example 1 50 2 1.9116 233 1.45 17.9 Example 2 50 1.5 1.75 6 223 1.34 19.7 Example 3 75 21.93 18 156 1.29 13.1 Example 4 75 1.75 1.76 7 242 1.51 18.8 Example 575 1.5 1.55 −6 229 1.64 16.7

TABLE 2 Average Average Average width of thickness CD CD CD width of MDof MD Tensile Tensile tensile CD coupons coupons strength strain moduluscoupons Units mm mm Mpa % Gpa mm Example 1 24.99 1.91 447 1.38 33 24.96Example 2 25.05 1.76 422 1.28 34.5 24.99 Example 3 24.91 1.95 329 0.9832.9 24.96 Example 4 25.03 1.79 518 1.19 43.6 24.99 Example 5 25.07 1.56535 1.45 36.6 24.99

TABLE 3 Average thickness of CD Composite Composite coupons tensilestrength tensile modulus Units mm Mpa Gpa Example 1 1.9 680 50.9 Example2 1.73 645 54.2 Example 3 1.91 486 46.0 Example 4 1.73 760 62.4 Example5 1.53 763 53.3

FIG. 4 illustrates the impact of carbon fiber length and theoreticalvoid volume on tensile strength according to an embodiment of theinvention. As shown in FIG. 4, the results of composite tensile strengthvs. void volume are plotted for the carbon fibers at 50 mm length(Examples 1 and 2) and 75 mm length (Examples 3-5). For Examples 3-5,the tensile strength increased as the theoretical void volume droppedtoward zero. As such, the composite tensile strength was the highest ator below 6% theoretical void volume. When a minimum gap of 1.5 mm wasused, the theoretical void volume was −7%. This result does not reflecta change in density for the material but instead reflects some of thematerial being pushed out at the edge of the plates due to excessivepressure.

FIG. 5 illustrates the impact of carbon fiber length and theoreticalvoid volume on tensile modulus according to an embodiment of theinvention. As shown in FIG. 5, the composite tensile modulus was plottedagainst theoretical void volume. The composite made with the 75 mm longcarbon fibers performed better than the composite made of 50 mm longcarbon fibers when the theoretical void volume was between 0 and 10%. Adrop in composite tensile modulus was observed when the theoretical voidvolume was negative due to the fact that the negative value correspondsto some of the material being pushed out of the plate. As such, when thetheoretical void volume is less than 10%, and, more precisely at 7% orlower, stronger composites are possible when the fiber length increases(e.g., from 50 to 75 mm).

Without wishing to be bound by theory, these results may be due to thefact that the lower void volume creates a more intimate contact betweenthe matrix polymer and the reinforcing carbon fiber. As a result, thefailure mechanism becomes dependent on the force needed to pull thecarbon fibers out of the matrix, and a longer fiber favors a betteranchoring of those fibers. At higher void volumes, this mechanism may beless important and may be overshadowed by the better distributionexpected to be obtained with the 50 mm carbon fibers.

These and other modifications and variations to the invention may bepracticed by those of ordinary skill in the art without departing fromthe spirit and scope of the invention, which is more particularly setforth in the appended claims. In addition, it should be understood thataspects of the various embodiments may be interchanged in whole or inpart. Furthermore, those of ordinary skill in the art will appreciatethat the foregoing description is by way of example only, and it is notintended to limit the invention as further described in such appendedclaims. Therefore, the spirit and scope of the appended claims shouldnot be limited to the exemplary description of the versions containedherein.

That which is claimed:
 1. A fiber-reinforced nonwoven composite,comprising: a plurality of carbon fibers, said plurality of carbonfibers having an average fiber length from about 50 mm to about 125 mm,wherein the carbon fibers comprise from about 10% to about 90% by weightof the composite; and a polymer matrix comprising a plurality ofpolymeric staple fibers, wherein the polymeric staple fibers comprisefrom about 10% to about 90% by weight of the composite, wherein thefiber-reinforced nonwoven composite has a composite density from about 3g/cm³ to about 5 g/cm³ and a theoretical void volume from about 0% toabout 10%.
 2. The fiber-reinforced nonwoven composite according to claim1, wherein the plurality of carbon fibers comprises uncrimped carbonfibers.
 3. The fiber-reinforced nonwoven composite according to claim 1,wherein the fiber-reinforced nonwoven composite comprises a theoreticalvoid volume from about 0% to about 7%.
 4. The fiber-reinforced nonwovencomposite according to claim 1, wherein the plurality of carbon fiberscomprises a linear mass density from about 0.1 dtex to about 1.0 dtex.5. The fiber-reinforced nonwoven composite according to claim 1, whereinthe plurality of polymeric staple fibers comprises at least one of apolyester, a polycarbonate, a co-polyester, a polyamide, a polyphenylenesulfone, an engineering polymer, or any combination thereof.
 6. Thefiber-reinforced nonwoven composite according to claim 5, wherein theplurality of polymeric staple fibers comprises a polyester.
 7. Thefiber-reinforced nonwoven composite according to claim 1, wherein theplurality of polymeric staple fibers comprises an average length fromabout 1 mm to about 100 mm.
 8. The fiber-reinforced nonwoven compositeaccording to claim 1, wherein the plurality of polymeric staple fiberscomprises a linear mass density from about 1.0 dtex to about 3.0 dtex.9. The fiber-reinforced nonwoven composite according to claim 1, whereinthe fiber-reinforced nonwoven composite comprises a basis weight fromabout 500 gsm to about 5000 gsm.
 10. The fiber-reinforced nonwovencomposite according claim 1, wherein the fiber-reinforced nonwovencomposite comprises an average thickness from about 1 mm to about 3 mm.11. The fiber-reinforced nonwoven composite according to claim 1,wherein the fiber-reinforced nonwoven composite comprises one or more ofthe following: a tensile modulus from about 15 GPa to about 50 GPa; atensile strength from about 140 MPa to about 600 MPa; a flexural modulusfrom about 15 GPa to about 50 GPa; and a flexural strength from about290 MPa to about 465 MPa.
 12. The fiber-reinforced nonwoven compositeaccording to claim 1, wherein the polymeric staple fibers comprise fromabout 20% to about 80% by weight of the composite.
 13. Thefiber-reinforced nonwoven composite according to claim 1, wherein thepolymeric staple fibers comprise from about 30% to about 70% by weightof the composite.
 14. The fiber-reinforced nonwoven composite accordingto claim 1, wherein the carbon fibers comprise from about 20% to about90% by weight of the composite.
 15. The fiber-reinforced nonwovencomposite according to claim 1, wherein the carbon fibers comprise fromabout 30% to about 90% by weight of the composite.
 16. Thefiber-reinforced nonwoven composite according to claim 1, wherein theplurality of carbon fibers includes (i) a first group of carbon fibersaligned in a first direction in a first plane and (ii) a second group ofcarbon fibers aligned in a second direction in a second plane, andwherein the second direction is located from 20° to 90° relative to thefirst direction.
 17. The fiber-reinforced nonwoven composite accordingto claim 1, wherein the fiber-reinforced nonwoven composite consists ofthe plurality of carbon fibers and the polymeric matrix, wherein thepolymeric matrix comprises a polyethylene terephthalate accounting forabout 10% to about 90% by weight of the composite.
 18. Thefiber-reinforced nonwoven composite according to claim 1, wherein thefiber-reinforced nonwoven composite consists of the plurality of carbonfibers and the polymeric matrix, wherein the polymeric matrix comprisesa polyethylene terephthalate accounting for about 20% to about 80% byweight of the composite.
 19. The fiber-reinforced nonwoven compositeaccording to claim 1, wherein the fiber-reinforced nonwoven compositeconsists of the plurality of carbon fibers and the polymeric matrix,wherein the polymeric matrix comprises a polyethylene terephthalateaccounting for about 30% to about 70% by weight of the composite. 20.The fiber-reinforced nonwoven composite according to claim 1, whereinthe plurality of polymeric staple fibers comprises a polyethyleneterephthalate accounting for about 30% to about 70% by weight of thecomposite, and the carbon fibers comprise from about 30% to about 70% byweight of the composite; wherein the fiber-reinforced nonwoven compositecomprises an average thickness from about 1 mm to about 3 mm and has abasis weight from about 2000 gsm to about 5000 gsm.